DE 42 34 868 C2 discloses a valve train comprising a finger lever that is mounted at one end through a ball-and-socket joint formed by a joint socket and a spherical joint head of a support element that is connected to a hydraulic medium supply of the internal combustion engine. The finger lever comprises a spray bore extending through the joint socket for lubricating and/or cooling a driven contact surface of the finger lever—in this document, a roller actuated by a cam of a camshaft. Pressurized hydraulic medium from the hydraulic medium supply is transported through a hydraulic medium passage extending within the support element via a supply bore in the joint head into a depression of the joint socket situated adjacent to the semispherical portion and leaves this through the spray bore that is directed toward the roller. The hydraulic medium serves at the same time for the lubrication of the joint contact region between the joint head and the joint socket.
In this configuration, the spray bore and the supply bore are in permanent hydraulic communication with each other, so that, during the operation of the internal combustion engine, the roller is permanently sprayed irrespective of the stroke position of the gas exchange valve. A drawback arising from this is the hydraulic medium stream that is required alone for this spraying and that, particularly in the case of multi-valve internal combustion engines, can add up to form a considerable share in the delivery flow from the hydraulic medium supply, i.e. in the drive performance of the hydraulic medium pump, and can thus constitute a larger contribution to the so-called mean friction pressure as a measure of the power dissipation of the internal combustion engine that is always to be kept as low as possible.
The above discussion applies equally to valve trains known to a person of ordinary skill in the art comprising a rocker arm which, in length direction of its arm, has a central joint socket in place of an end joint socket and is mounted through a ball-and-socket joint on a joint head of a so-called suspended support element.